1. Field of the Invention
This invention relates to an improved skin engaging member for use in razor blade cartridge assemblies and shaving systems of the wet shave type. The present invention resides broadly in providing the skin engaging cap and/or guard surfaces with configurations which deliver a shaving aid as the razor is dragged across the skin. Suitable shaving aids include lubricants, whisker softeners, razor cleaners, medicinal agents, cosmetic agents or combinations thereof. This invention also relates to a novel method of manufacturing the skin engaging member of the present invention.
2. Description of the Prior Art
In shaving systems of the wet shave type, factors such as the frictional drag of the razor across the skin, the force needed to sever hairs, and irritation of pre-existing skin damage can create a degree of shaving discomfort. Discomfort, and other problems accompanying wet shaving systems, can be alleviated by the application of shaving aids to the skin. Shaving aids may be applied prior to, during, or after shaving. A number of problems accompany the use of pre- and post-applied shaving aids. Pre-applied-shaving aids can evaporate or can be carried away from the site of application by repeated strokes of the razor. Post-applied-shaving aids are not present on the skin during shaving and thus their application may be too late to prevent an unwanted affect. Both pre-applied and post-applied shaving aids add additional steps to the shaving process.
Proposals have been made to incorporate a shaving aid, e.g. lubricant, whisker softener, razor cleanser, medicinal agent, cosmetic agent or combination thereof, into a razor, e.g. by depositing a shaving aid in a recess on the razor, by incorporating a shaving aid directly into one or more molded polymeric components of the razor, by adhesively securing a shaving aid composite to the razor, and by use of a mechanical connection between a shaving aid composite and the razor. A water-soluble shaving aid, e.g. polyethylene oxide, has been mixed with water insoluble matrix material, e.g., a polystyrene polymer, to form an insoluble polymer/soluble shaving aid composite as in U.S. Pat. No. 4,170,821 to Booth and U.S. Pat. No. 5,113,585 to Rogers. The composite has been mounted on razor and shaving cartridge structures, adjacent the shaving edge or edges, of single or multiple blade shaving systems. Upon exposure to water, the water-soluble shaving aid leaches from the composite onto the skin. These composites tend to release large amounts of shaving aid in the first few shaves and dramatically less shaving aid in subsequent shaves. Furthermore, extruded composites with relatively large amounts of shaving aid (up to 80% by weight) and relatively low amounts of water insoluble matrix material (as little as 20% by weight) are relatively weak and have a tendency towards mechanical failure, both in assembly and in use. Increased mechanical strength can be obtained with increased amounts of the insoluble matrix material. However, such increase reduces the releasability of the shaving aid material.
Commercial lubricating strips, especially those with high levels of polyethylene oxide lubricant like those described in U.S. Pat. No. 4,170,821 to Booth and U.S. Pat No. 5,113,585 to Rogers, tend to deteriorate after use. Leach rate varies during the course of shaving and typically about 50% of the polyethylene oxide is trapped in the strip. The selection of the polyethene oxide carrier (i.e., the non-water soluble matrix material) is limited to a carrier that has a low melting or softening temperature and is at least partially miscible with polyethene oxide. In addition, because the strip is made at a high temperature of approximately 180.degree. C., additives such as fragrances and plasticizers are difficult to incorporate in the strips.
U.S. Pat. No. 4,872,263 to Etheredge, III, issued Oct. 10, 1989, discloses a lubricating device comprised of a porous matrix impregnated with a particular acid soap. The impregnated matrix is covered with a water insoluble perforated sheet material in an effort to prevent the lubricant from eroding too quickly and to provide a smooth "massaging" effect on the skin. These lubricating devices have not met with commercial success. These lubricating devices are expensive to manufacture due to the additional assembly required of the sheet-over-matrix design. They also tend to swell and delaminate when affixed to the razor cartridge with glue. Furthermore, the soft porous matrix does not lend itself to economical mechanical means of affixing the strip to the razor cartridge.
We have demonstrated that it is feasible to produce a two-component, controlled-release shaving device consisting of an outer surface layer with openings and an internal shaving aid-containing layer. The potential advantages of using the device are to 1) maintain a uniform surface appearance, 2) achieve near zero-order release profile (i.e. approximately constant release) of the shaving aid after 1-4 shaves, 3) minimize material degradation, 4) minimize shaving aid material trapped in the device, 5) provide a shaving aid device which is easy to manufacture and/or 6) to provide a shaving aid device which is easily integrated with a razor cartridge system. These and other objects of the present invention will be evident from the following: